A 6.47 mm high firefly sits on the axis of, and 12.3 cm in front of, the thin lens A, whose focal length is 5.77 cm. Behind lens A there is another thin lens, lens B, with a focal length of 20.9 cm. The two lenses share a common axis and are 58.1 cm apart.

Is the image of the firefly that lens B forms real or virtual?
a. real
b. virtual